How do I start building a life for myself again?

In highschool and early 20s I had a lot of friends, very social, hobbies, working out and pretty typical life. Fast forward now, after lots of mistakes, many stints of addiction, depreciated self esteem and mental health problems, I am completely and utterly alone and feel like I’m just watching the best years of my life go by. I feel so lost and stuck and I just lost my mom and it was hard watching her slowly die over the years and how it affected my dad and family. My self worth is non existent and I see where other ppl are my age and I just feel worse about myself. How do I get back to having friends, living life, enjoying things, and not feeling so worthless all the time? I’m at a point now that I honestly feel like nobody wants to be around me because I mean who would? I’m very much a loser. The only thing I find comfort in is drugs and getting sober will be pointless because I’ll be alone and sober. I am aware of the blessings I have, the body I’ve been given, and everything in between but none of that means anything without people to share it with.